I have a 1993 Bonneville with supercharge. The engine now has over 310,000 km. The car is still running great and feel great on the road. I took the car out for a long highway and mountain road (over 1100 km). Each time I stop for gas, I checked for engine oil level. I have noticed the oil went down slightly. Top up to a full mark with 10W30 oil that took about 3/4 of the 1 litter bottle. Drive again for 700 km more, I had to top it up to a full mark again with the rest of the oil that is 1 litter for 1800 km.
I decided to replace the PCV valve locate on top of my supercharger unit with Canadian Tire part as it is the only store around. ( I kept the old part just incase). Immediately I smell a strong gas or odour of unburned fuel somewhere under the vehicle when I stop at the rest stop (about 15 min city drive). I drove for another 1300 km for the remaining of the trip with the new PCV valve and the odour slowly gone, the oil consumption drop to almost 3/4 of a litter (little more than half of litter). My exhaust tail pipes is black but no oil and the rear bumper is clean and there is no visible residue of oil along the rear bumper either. I would expect my exhaust tail pipes to have a tan deposit in color not black after a long trip like this.
I have a few questions: My exhaust tail pipes deposit should not have black but tan in color right? does this mean that my car is start to burn oil? It passed E-test about 6 months ago.
Why did it smell gas or unburned fuel odour when I changed the PCV valve? The odour is gone now. Should I expect a car problem soon?
Any ideas?